Special Report: up to 6 serial killers murdered dozens over 20-year span in Denver metro area

An average of twice a year between 1975 and 1995, the nude body of a young girl or woman appeared along rural roads and fields encircling Denver. Many were teen-agers.

Most of the murders were never solved, and a new effort is underway by a loose-knit group of cold case detectives from around the metro area who are trying to find the answers in the decades-old killings.

Those detectives have submitted evidence from various cases the Colorado Bureau of Investigation for DNA testing, hoping new technology might identify a prolific killer — or killers.

The work is driven by a simple belief: That anywhere between four and up to a half-dozen serial killers were stalking Denver-area streets between 1975 and 1995, according to detectives, murdering an untold number of women. Some investigators believe the number of victims may be as few as 17 — or as many as 38.

Authorities believe convicted serial killer Vincent Groves, who died in prison, was responsible for as many as 11 murders.

Melanie Suzanne Cooley
Age: 18
Occupation: high school student
When disappeared: April 15, 1975
When found: May 2, 1975
Where last seen: Nederland High School
Where found: Coal Creek Canyon, Jefferson County
Cause of death: Bludgeoned in head with rock
Unusual circumstances: body found nude

Kirk Mitchell is a general assignment reporter at The Denver Post who focuses on criminal justice stories. He began working at the newspaper in 1998, after writing for newspapers in Mesa, Ariz., and Twin Falls, Idaho, and The Associated Press in Salt Lake City. Mitchell first started writing the Cold Case blog in Fall 2007, in part because Colorado has more than 1,400 unsolved homicides.